1. Field of the Invention
The present invention relates to an image reading apparatus for reading images from a document, a control method for the image reading apparatus, and a program for having a computer execute the control method.
2. Description of the Related Art
Some known image reading apparatuses with an automatic document feeder (hereinafter “ADF”) have a mode called a “skimming mode” that is a reading mode using the ADF. In the skimming mode, an image reading apparatus allows its document reader fixed at a predetermined reading position to read images from a document while allowing its ADF to feed the document at a constant speed.
To maintain the quality of images read from a document, some image reading apparatuses having a skimming mode perform a predetermined operation during intervals between documents being fed. For example, Japanese Patent Laid-Open No. 2002-300394 discloses an image reading apparatus that monitors fluctuations in lamp intensity during intervals between reading individual documents, and adjusts the lamp intensity if the amount of fluctuations in lamp intensity exceeds a certain level.
In another instance, Japanese Patent Laid-Open No. 2000-209403 discloses an image reading apparatus having a skimming mode, which prohibits the execution of correction processing during intervals between reading individual documents if the distance between the document currently passing through a reading position and the subsequent document falls below a certain level.
To read a document with images on both sides, many image reading apparatuses having a skimming mode provide an ADF that allows the document to pass through a reading position three times. Specifically, after the first surface (hereinafter called front side) is read, the document is reversed. Then, after the second surface (hereinafter called back side) is read, the document is reversed again so that all documents are ejected consistently with the same side up (idle reverse ejection).
To increase productivity when a document with images on both sides is read, some image reading apparatuses with the above-described ADF provide a high-speed double-side reading mode in which two documents are transported along a transport path in the ADF. In the high-speed double-side reading mode, after the back side of the previous document is read, the front side of the next document is read simultaneously with the idle reverse ejection of the previous document. That is, the order of a plurality of documents that pass through a reading point is as follows: first document (front side)→first document (back side)→second document (front side)→first document (idle reversal)→second document (back side)→third document (front side)→second document (idle reversal)→third document (back side)→. . . .
However if, as described above, the execution of correction processing during intervals between reading individual documents is prohibited when the distance between the document currently passing through a reading position and the subsequent document falls below a certain level, correction to the subsequent document may not be properly made. In other words, the known image reading apparatuses described above may not be able to produce high-quality read images from documents.